Remove bogus unsquashfs invocation: it cannot work
Remove bogus unsquashfs invocation: it cannot work

This is because the Dockerfile runs inside a Cedar image, and Cedar
doesn't have unsquashfs.

I reported this to https://github.com/ddollar/heroku-docker/issues/2
whence it came.

fdr/hsup-fdr,fdr/hsup-fdr,heroku/hsup,heroku/hsup